Things that make it cheaper are;
Crime free post code. If you live in a city centre it's more expensive, if you live in a conservative rural village, cheaper.
Age and experience. Young and just got the bike, no experience more of a risk. Old with lots of no claims bonus and a clean license, cheaper.
Then there are the bits and bobs. Not using it to commute to work, being married, limited mileage, can show them you are a sensible person.
Security devices, there are lists of what counts towards a discount.
Having advanced riding skills, not sure what they are, never had any.
By you getting a 125 your postcode and age I'm guessing may be your biggest enemy. Have you got a granny that lives in the sticks?